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Biological Calendars: Using Degree-Days and Plant Phenology to Predict Pest Activity Dan Herms

Learn how to use phenological events and degree-days to track plant and pest development, and schedule pest management in landscapes and nurseries.

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Biological Calendars: Using Degree-Days and Plant Phenology to Predict Pest Activity Dan Herms

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  1. Biological Calendars: Using Degree-Days and Plant Phenology to Predict Pest Activity Dan Herms Department of Entomology The Ohio State University Ohio Agricultural Research and Development Center Wooster herms.2@osu.edu

  2. Landscapes and nurseries are diverse ecosystems

  3. Objectives: • Degree-days • Phenology and biological calendars • OSU Phenology Garden Network • National Phenology Network

  4. Development rate of plants and insects is temperature dependent.

  5. Daily temperature readings can be used to calculate growing degree-days, which is a measure of accumulated heat.

  6. Degree - Day: Amount of heat accumulated over a specified base temperature during a 24 hour day.

  7. Base Temperature: • Temperature above which degree-day • accumulation is calculated. • Ideally, the lower temperature threshold.

  8. Lower Temperature Threshold: Temperature below which no growth or development occurs in the species of interest.

  9. Cumulative Degree - Days: Number of degree-days accumulated during a specified time interval (i.e. since the beginning of the year).

  10. Key Point: Degree-days only have meaning if base temperature and starting date are specified.

  11. Calculating Degree-Days • Average method • Modified average method • Modified sine wave

  12. Average Method: DD = Avg Temp – Base Temp Max = 70, Min = 40 70 + 40 2 - 50 = 5 DD

  13. Modified Average Method: When minimum temperature drops below base temperature, set minimum = base temp. More accurate when minimum drops below base.

  14. Max = 70, Min = 40 Average Method: 70 + 40 2 - 50 = 5 DD Modified Average Method: 70 + 50 2 - 50 = 10 DD

  15. Modified Sine Wave Method:

  16. Limitations of Degree-Day Models: • Insect response to temperature is not linear. • Lower temperature threshold known for very • few species. • Measured temperatures not the same as those • experienced by the pest. • Degree-days are cumbersome to track.

  17. Since plant development is temperature-dependent, phenological events of plants can also be used to track degree-days… and predict pest development.

  18. Phenology: The study of recurring biological events. “The oldest science.”

  19. Hypothesis: the flowering sequence of ornamental plants can be used as a biological calendar to predict pest activity and schedule pest management appointments.

  20. The hypothesis was tested in Secrest Arboretum by • monitoring over the past 7 years: • The phenology of 45 key arthropod pests of • ornamental plants (e.g. egg hatch, adult emergence). • 2. The flowering sequence of 75 taxa of woody ornamental plants.

  21. Key Phenological Events First bloom: date first flower on the plant opens to reveal pistils and / or stamens. Full bloom: date 95% of flowers have opened (e.g. 1 out of 20 buds remains closed).

  22. The flowering sequence of plants can be used as a biological calendar to track degree-days and schedule pest management appointments. S. Gage, Michigan State Univ. D.G. Nielsen, Ohio State Univ.

  23. Phenological Sequence for Secrest Arboretum Species Event Degree-Days Red Maple first bloom 45 Eastern Tent Caterpillar egg hatch 92 Eastern Redbud first bloom 197 Gypsy Moth egg hatch 203 Snowdrift Crabapple first bloom 214 Birch Leafminer adult emergence 231 Common Lilac first bloom 238 Pine Needle Scale egg hatch 301 Vanhoutte Spirea first bloom 309 Lilac Borer adult emergence 336 Black Cherry first bloom 376 Euonymus Scale egg hatch 463 Black Locust first bloom 503 Bronze Birch Borer adult emergence 519 Mountain-laurel first bloom 565 Juniper Scale egg hatch 579 Littleleaf Linden first bloom 878 Japanese Beetle adult emergence 966

  24. Red maple, Acer rubrum

  25. Corneliancherry Dogwood, Cornus mas

  26. Star Magnolia, Magnolia stellata Border Forsythia, Forsythia x intermedia

  27. Eastern tent caterpillar egg hatch

  28. Saucer Magnolia, Magnolia soulangiana Bradford Callery Pear, Pyrus calleryana ‘Bradford’

  29. European pine sawfly egg hatch

  30. PJM Rhododendron, Rhododendron x ‘PJM’ Serviceberry, Amelanchier grandiflora

  31. Spruce spider mite egg hatch

  32. Redbud, Cercis canadensis

  33. Gypsy moth egg hatch

  34. Crabapple, Malus spp.

  35. Common lilac, Syringa vulgaris

  36. Pine needle scale egg hatch

  37. When red buckeye (Aesculus pavia) blooms: Hummingbirds return

  38. Black cherry, Prunus serotina

  39. Optimal timing for aerial Bt applications for gypsy moth

  40. Miss Kim Lilac, Syringa patula ‘ Miss Kim’

  41. Oystershell scale egg hatch

  42. Black locust, Robinia pseudoacacia

  43. Bronze birch borer adult emergence

  44. Littleleaf Linden, Tilia cordata

  45. Egg hatch of soft scales

  46. Key premise: phenological sequence remains constant from year-to-year.

  47. http://www.oardc.ohio-state.edu/gdd

  48. How accurate is a biological calendar developed in one region when it is used in another? We’ll soon find out.

  49. The OSU Phenology Garden Network Coordinators: Denise Ellsworth Summit County Extension Dan Herms OARDC

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